As a veteran of countless military campaigns and death-defying adventures, G.I. Joe has seen it all. He's captured pygmy gorillas and hunted white tigers, fought terrorists at home and worked to save the world from environmental disaster.

Through it all, several generations of boys and girls have commanded his every move. Whether he's parachuting into a living room fortress made of cushions, or dodging enemy fire in back-yard foxholes, America's first action hero has become a legend in his own time.

"I have G.I. Joe to thank for a lot in my life," said Ace Allgood, a Minneapolis superfan and collector of G.I. Joe memorabilia. "He could be anyone I wanted him to be — a tiger hunter on Monday, a soldier on Tuesday, or go in search of mummies on Wednesday."

But as G.I. Joe enters his fifth decade, he is at a crossroads. Superheroes, transforming robots and intergalactic warriors now rule the hearts and minds of kids. Is there still room for this real American hero?

• • •

In 1964, G.I. Joe enlisted in the U.S. military and quickly became the emblem of the courageous American soldier. Standing 12 inches tall, he looked like an everyman soldier yet with a ruggedly scarred face.

So adept at combat was he that he represented all four branches of the armed forces. Some days he was a bayonet-slinging soldier. Other days he was a pilot in an orange flightsuit, or a sailor sent to bombard enemy ships. He drove a "Five Star Jeep," shining searchlights on crouching enemies, and explored the sea in his state-of-the-art "frogman" suit.

As the United States was becoming entrenched in the Vietnam War, G.I. Joe struck a chord. "He mirrored the social and cultural movements of the country," said Minnesota Historical Society senior curator Adam Scher.

"He came out of the Vietnam era to stand up for patriotism and give everyone hope and belief that the government and America were doing the right thing," said Jordan Hembrough, host of the Travel Channel's Toy Hunter.

By 1968, the country was growing weary of the Vietnam War and G.I. Joe reinvented himself. He became a daring adventurer, sent to rescue mummies and ancient artifacts. He wrestled bears and tigers and took on abominable snowmen, giant clams and massive spiders.

To entice a new generation of fans, G.I. Joe grew fuzzy hair and sometimes sported a beard. He developed the now-famous "Kung-Fu Grip," a technique to better hold his weapons and equipment. His popularity soared.

Longtime fans keep the memory of these years alive with their Joe rooms.

"It's reliving your childhood — those times you had when you were a little kid and you had no worries," Allgood said. The 46-year-old's basement is lined with floor-to-ceiling glass cases crammed with G.I. Joe collectibles. Closets store even more "fanfare," which he regularly takes to conventions such as "Joelanta" or "GIJoe­Con."

Allgood even proposed to his wife at a G.I. Joe convention. She agreed, under one condition: His Joe room had to move from his living room into their basement.

• • •

As the 1970s came to a close, problems arose again for G.I. Joe — this time as a result of the petroleum crisis. The cost of oil used to fuel his foot-high figure skyrocketed, so G.I. Joe went under the knife and shrunk to 8 inches. The move didn't go over well with fans. "It was an unmitigated disaster," remembered Jim Kitchen, 45, of St. Paul, Minn.

With no superpowers to hang his hat on, G.I. Joe slipped into obscurity as interest shifted to action figures from a galaxy far, far away.

At the beginning of the 1980s, G.I. Joe's career was resuscitated when he was recruited to take on a new, powerful foe: a ruthless terrorist organization called Cobra.

By this time, he had shrunk to 3¾ inches, but he had an army of new soldiers to help him fight terrorism. Snake Eyes, Duke and Scarlett represented America's melting pot.

Suddenly, G.I. Joe's career was lightning in a bottle all over again, spawning cartoons, comic books, video games and movies — where his battles with Cobra were well-documented. He drove around in slick new armored vehicles and piloted a giant aircraft carrier. He slipped into an "eco-suit" to stop bad guys from dumping toxic sludge.

But by 1995, G.I. Joe was weary of sharing the spotlight with Luke Skywalker, Donatello and a team of mighty morphing martial artists. The competition was fierce and G.I. Joe was fading.

During the next decade, G.I. Joe tried to make a comeback. He regained his original height, and in 2004 was inducted into the National Toy Hall of Fame, where he joined his friends Mr. Potato Head and, of course, Barbie.

• • •

Now, at 50, many of his fans are wondering if G.I. Joe's career is nearing the end.

Short, a serious collector of G.I. Joe memorabilia, has spent $35,000 in a single day at toy auctions: "For the most part, I don't think children care or even know (who) G.I. Joe is."

Hasbro, the company that makes G.I. Joe, says it plans "exciting new publishing ventures," more movies and action figure sets.

But while movies may rekindle his memory, his final mission can't be far away.

"I can remember how excited I was on Christmas in 1973 when I was first introduced to him,'' Kitchen said. "All those memories I have are going to slip away. And all those adventures he and I had? Who will remember those?"